Pedal Powered Boats

Did you try the hollow CF braid that's made for this job? I've not tried it, but have hear good reports about it being a very easy way to make CF tubes and spars. It has the advantage of a double approximately 45 deg wrap, provided the right size of braid is chosen.

I'd guess that using hollow braid would be a lot easier than using uni tape for this job.

Jeremy

 

Carbon Fiber shaft

I considered using the carbon fiber sleeves instead of the winding the unidirectional tape. My intuition is that the over/under weave of the CF sleeves would make it less stiff than winding consecutive layers of unidirectional tape alternating from +45 to -45 degrees. That is the same concept of why biaxial material is stronger than woven material. The sleeves cost about twice as much as the unidirectional tape. I didn't try using the sleeves but I think you are right - they probably would be quicker to install. Since my primary goal for the CF was to improve the torsional stiffness of the drive shaft I went with the spiral wound approach. That said, I am interested if anyone has used the CF sleeves and what torsional stiffness they measured for this type of application.

 

Here is a more or less commercial version of the shaft you are describing, but hollow: http://www.graphitestore.com/itemDetails.asp?item_id=1372&prd_id=99&cat_id=34&curPage=1

The manufacturer may have longer lengths and diameters or perhaps they can be spliced with metal since the whole tube doesn't always need to be flex' depending drive design. Maybe they can supply specks if contacted directly to see if that is about what you need. Rick, who generally likes to hand make just about all his parts, had someone make him a CF drive shaft to his specks, so the self make process may be challenging....

I picked up a CF shaft golf driver at Goodwill for $2 and the tapered hollow shaft is very stiff, extremely light and torsionally compliant for lower power ratings that I use in my gadgets, at about 50 watts. I suspect something like that would hold up at much higher demands but don't know the formula they use or have any measurements to prove it....

Porta

 

I really like that box because of its light weight. Here is another thing that is being modified by some pedallers which is compact http://www.traditionalwoodworker.co...ll-with-Chest-Plate-1_2/productinfo/500-0344/ There are other even smaller versions but maybe not hold up to racing stresses though...

Porta

 

carbon fiber flex shaft

Rick did have a CF drive shaft built for him. He measured it at 16 Nm/rad which is not as stiff as he wanted. The link you provided said most of the CF is oriented longitudinally which does little for torsional stiffness. The torsional stiffness is proportional to the 4th power of the shaft radius so a 1/2" shaft has a 16x advantage over a 1/4" shaft. What you really need for torsional stiffness is spiral wraps at +/- 45 degrees. The link did say they use pre-preg CF which would be an improvement over my handmade process. I think the ideal process would be machine tightly wound unidirectional pre-preg CF over an aluminum mandrel at alternating +/-45 degrees then cured in an oven. My 8' drive shaft doesn't fit in my oven so I rely on Florida sunshine!

 

Jeremy we realy miss you on E.S. are you alright? Did you fix your internet problem? I tried emailing you but your acount is set up not to alow it. Hope to get you back soon.

 

Hi Arlo,

Thanks, all's OK, I've just seen this, logged in to ES and posted.

Jeremy

 

hi guys.

right now i have few kayaks.

one off them a natives ultimate 14.5 is ropel by a bass yak kit. witch i love.

here it is



the prob its NOT self propel..not allowed in self propel fishing derbies.

many people there have hobies pedel yaks and many paddling.


me i would love to keep my kit on mine..but turn it into self human powerd.

reading the coach dave response it got me thinking.

is there is a simple way to keep it all..but make that motor go..wit my powerd.....would love to keep my hands free.most off time taugh...like an hobies.

its a little project i would love to do. this winter.

thanks for all help.

joco

 

if somebody use a little pedal systeme to charge a 12volt batteries is this SELF PROPEL..?

i want to make it simple and small.

joco

 

pedal powered generator

Joco,

I think a pedal powered generator could work for your application. To meet the self propelled criteria you should eliminate the battery and connect the generator directly to your existing motor. You will still have the ability to paddle when your hands aren't on fishing equipment. You could try using your existing seat to see if that is comfortable while pedaling. I found that for hours of sustained hard pedaling recumbant bicycle style seats are quite comfortable. However for intermittent easy pedaling to maneuver while you are fishing your current seat may be fine.

Dave

 

new guy, old question......cat vs mono

I had my heart set on building a pedal powered cat this winter until I saw a posting from several years ago where someone (Rick maybe?) said that a cat required 39% more power to reach the same speed as an equivelent stabilized mono-hull. I was going to make two hulls 18 feet long and 8 inches wide with plywood sides and rounded strip bottoms. Cross section would be consitent for the center 8 feet and have sharp bow and stern. Hull separation to be 6 feet center to center. Drive system would be bicycle components to a sturdy angle drive and then the long flex shaft to the rear to an airplane prop to start with.
This will be used on sheltered ocean areas where conditions can range from flat calm to 2 foot wind chop, likely in the same trip. I won't be racing but like my recumbent lowracer, I do like to get where I am going at the best pace possible given the conditions.....
Would I be correct in thinking that the difference in potential performance of these two types of boats would get closer as the waves get higher? I am wondering also if a useful compromise would be a mono-hull with outriggers designed for low drag when they touch flat or calm water, but with increased displacement up higher that would keep the boat upright as the chop increases. Most people seem have the outriggers biased more towards the stern...I can see that this makes more room if you need to paddle, but is there a handling (seaworthy-ness) advantage to this as well?
Thanks, Glen

 

Cat vs Mono

Cat vs mono, this has been debated many times not only on this website but many others. The stabilised monohull is faster but which one, cat or mono goes back to what you want to use the boat for. Mono for speed or cat for stability. As far as wave height goes you will get wet with either boat. I'm probaly biased as my boat is a stabilised monohull with the outriggers set to just skim the surface. Having the outriggers tapering out to a larger section higher up will give you more chance of surviving a knockdown. Giving yourself room to paddle is a good idea, long slender outriggers (1/2 to 3/4 of boat length) work better in rough water, having support poles at each end keeps them solidly in position and not pitching up and down. One other thing to consider is windage, a boat that is narrow and deep will slice the waves well but will be hard to turn. Keep the above water side section low and angled, flat high sides will make the boat hard to handle when the wind is strong. Hope all of this helps.

Ian

 

Thanks Ian,
I am thinking I may cover both types of boats by building two hulls that can be either used as two separate monohulls equipped with outriggers, or be attached to a frame and used as a cat. Sounds like the outriggers should be longer than I had imagined and I should look at the hull displacement a little more carefully. I had not really given the windage issue enough consideration and was planning vertical plywood sides, mostly because of ease of construction. I will either change the profile above the water line or reduce the deck height to minimize that effect. Not having enough room to paddle is one criticism I have seen of the Hobie Aventure Island as well.
I appreciate your input Ian and I am amazed at all the great ideas people have put forward to this site. I plan to set up a site to detail the construction and testing of this project, what ever it turns out to be!

Glen

 

Hello again Ian,

Are there pictures of your boat(s) on the net? I'm wondering what sort of hull configuration you used, especially the beam.......and if you achieved the level of performance you were expecting/hoping for. Thanks

Glen

 

Glen
If you trawl through this thread I have a few pics up of my boats and the trials and errors I've had. Pics are of my latest boat which I have modified a few times, the pic boat4 is the latest. Boat specs are length 5metres beam 2.2 metres, total weight including gearbox is 31kg. The 5 metre length is because its the biggest I can fit in my garage, the boat unbolts for transport on the car roofrack. The boat is designed for lakes and rivers but have been on the bay on a calm day. Will be away travelling in the next few weeks and will have net access occasionally, good luck with your boat.

Ian